Method and apparatus for controlled lubrication during metal drawing

ABSTRACT

A measured quantity of lubricant in an amount that will be completely utilized is supplied through a conduit by an injector to metal being drawn. The quantity injected is accurately controlled and the flow from the conduit is positively stopped following the discharge of the measured quantity. This is accomplished by reducing the pressure within the supply conduit upstream from its discharge orifice to a level lower than that at the orifice after a predetermiend time delay that follows the injection.

United States Patent Stofey et a1.

[ Nov. 26, 1974 METHOD AND APPARATUS FOR CONTROLLED LUBRICATION DURING METAL DRAWING [75] Inventors: William D. Stofey, Wickliffe; H.

Edward Judd, Newbury, both of Ohio [73] Assignee: Etna Products, Inc., Chagrin Falls,

Ohio

[22] Filed: July 30, 1973 [21] Appl. No.: 383,558

[52] US Cl. 72/45 [51] Int. Cl. B2lc 9/00 [58] Field of Search 72/41, 43, 44, 45, 283;

[56] References Cited UNITED STATES PATENTS 1,471,669 10/1923 Miller .1 72/45 2,302,857 11/1942 Harder 72/44 2,351,710 6/1944 Sanders i 72/41 2,667,236 1/1954 Graves 184/56 A 3,427,840 2/1969 Richter 1. 72/44 3,566,641 3 1971 Sauve 72 45 FOREIGN PATENTS OR APPLICATIONS 1,062,260 8/1952 France 72/283 Primary Examiner-C. W. Lanham Assistant ExaminerE. M. Combs Attorney, Agent, or FirmWatts, Hoffmann, Fisher & I-Ieinke Co.

[5 7] ABSTRACT A measured quantity of lubricant in an amount that will be completely utilized is supplied through a conduit by an injector to metal being drawn. The quantity injected is accurately controlled and the flow from the conduit is positively stopped following the discharge of the measured quantity. This is accomplished by reducing the pressure within the supply conduit upstream from its discharge orifice to a level lower than that at the orifice after a predetermiend time delay that follows the injection.

5 Claims, 3 Drawing Figures METHOD AND APPARATUS FOR CONTROLLED LUBRICATION DURING METAL DRAWING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the lubrication of metal during drawing.

2. Prior Art In cold forming of metal, as by drawing, lubricants are used. Soap is a common lubricant used for bench drawing of non-ferrous metals. For ferrous metals, soap is not as satisfactory and often the metal must be precoated, as with a phosphate. Oil with additives is also used, as a lubricant. All of these lubricants have nor-.

mally been applied by dipping the material in the lubricant, by flowing the lubricant onto the material during the drawing operation, or by a combination of the two.

Commonly problems are encountered in the initial mixing of the lubricant and in the control necessary to keep the lubricant solution in a usable condition. It is also difficult to dip coat the interior of long tubes, especially of small diameter. Typically, the lubricant drips from the metal during subsequent handling and prior to being drawn, and the disposal of large volumes of solution that form the bath for dipping, after use, creates a problem, especially with the present emphasis on ecology. Where oil is used as a lubricant, normally the product is not dipped, but rather the oil is flowed onto the product and recirculated, directly at the drawing machine. This creates a problem of charging the recirculation tank and changing the oil periodically. Further, in recirculation systems, chips and dirt accumulate in the lubricant and are redeposited on the metal being drawn. This leads to increased tool wear and scratching of the drawn material. Cleanliness in the area is very hard to maintain because of oil dripping from the applicators and spilling from the tank area. Even if the oil is kept clean by filtering during the use, it will eventually break down chemically and this will lead to lubricant failure and poor drawing. In addition, any recirculation system has the problem of plugged passageways and necessitates periodic cleaning.

A relatively new approach with which the present inventors have been working overcomes most of the above disadvantages by using a concept in which only the lubricant needed to perform the drawing operation is discharged and applied to the object being drawn. The bulk lubricant container itself forms the reservoir for this system and the lubricant is pumped directly from the container to the point of dispensing. Only the amount needed is dispensed at the proper time, directly adjacent to the forming operation. This eliminates the need for pre-coating the object and alsothe need for recirculation of the lubricant. The lubricant is advantageously applied with an injector that introduces measured quantities to a conduit from the injector leading to the workpiece, directly adjacent the drawing die. A substantial problem arose however, in preventing afterflow, which caused more lubricant to be deposited from one injection than needed, and also partially depleted the lubricant to be discharged from the conduit ,for the next cycle of lubrication. The excess lubricant defeated one purpose of the approach, which was to avoid the mess created by excess lubricant. Further, the subsequent shortage of lubricant for the next injection resulted in a difficult draw operation. It will be appreciated that if the amount of lubricant applied to the article being drawn is to be totally used by the drawing operation, the amount of lubricant must be measured and discharged with extreme accuracy, and the flow of lubricant must be stopped precisely after the needed quantity has been deposited.

SUMMARY OF THE INVENTION The present invention provides a lubricating system for a metal drawing operation, in which the amount of lubricant injected into a conduit for depositing at the drawing die is accurately measured and the flow accurately controlled to assure depositing of the proper amount at the proper time and to prevent additional lubricant from being deposited after the desired amount is applied, so that only the amount that will be totally used is dispensed.

In practice an injector is utilized to which lubricant is applied under pressure by a pump from the lubricant container. The supply of lubricant under pressure to the injector is controlled by a timer-operated, airactuated, three-way, valve. The injector has a measuring chamber and a discharge chamber, and automatically limits the amount of lubricant received from the pump. When lubricant is supplied under pressure to the injector, it injects a measured quantity from the discharge chamber through a discharge passage to a conduit that applies the lubricant to the: metal being drawn. At the same time, the measuring chamber receives a new quantity of lubricant. Upon removal of supply pressure, the injector transfers the lubricant received in the measuring chamber to the discharge chamber for the next cycle. In so doing, it temporarily reduces the pressure at the discharge passage of the discharge chamber. In accordance with the present invention, this pressure reduction is under control of a timer that establishes a predetermined time delay before the supply pressure to the injector is relieved. This delay allows residual pressure in the conduit leading to the point of lubricant application to be partially relieved through a continued discharge of lubricant. This continued discharge is part of the predetermined amount calculated to satisfy the needs of the drawing operation. The time delay during which supply pressure is maintained is coordinated with the amount of pressure relief obtained through the continued discharge, so that when the supply pressure is shut off and the injector recycles, the reduction in pressure in the conduit upstream from the discharge orifice will completely relieve residual positive pressure in the conduit, drawing back any lubricant that otherwise might continue to flow or drip.

As a result of the above, it is possible to positively stop the discharge of lubricant after a known quantity quent to the application of the desired amount, thereby preserving the accuracy of subsequent applications of lubricant and avoiding the use of excess lubricant over that required for the drawing operation.

Other objects, features and advantages of this invention will become more apparent from the detailed description that follows when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side view with parts in section and parts in elevation illustrating a general arrangement for supplying lubricant in accordance with the present invention to the inside of a tube during a drawing operation;

FIG. 2 is a diagrammatic layout showing the lubricant supply and control system for supplying lubricant to the injector used with the apparatus of FIG. 1; and

FIG. 3 is a longitudinal sectional view of an injector suitable for use with the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A draw bench suitable for practicing the method of the present invention and embodying the apparatus of the present invention is partially shown in FIG. 1 of the drawings. A tubular metal workpiece W is shown as it is drawn on a draw bench to change its diameter and length. The workpiece W is supported for longitudinal movement during the drawing operation by a tubular support 12 supported horizontally by stands 14, 15. The workpiece W surrounds a mandrel 16 and is drawn through a die 18 in a die stand 20, by a drawing mechanism, not shown, but well known in the art. Both the inside and'the outside surfaces of the tubular workpiece W are lubricated during drawing. The lubrication system for the inside only is described herein for purposes of illustrating the invention, but it will be understood that the system is applicable to the outside lubrication of the workpiece as well.

For the purposes of the present lubrication method, the lubricant should be applied directly adjacent the mandrel l6 and die 18, where the cold working and shaping of the workpiece W occurs. To supply lubricant to the inside surface of the workpiece W adjacent the mandrel 16, a supply conduit 22 which also acts as a mandrel support rod, is attached to the mandrel 16 at the upstream end thereof, considered in the direction of workpiece travel during drawing. The supply conduit 22 is supported in cantilever fashion from an injector support and mandrel support stand 24 adjacent the back end of the tubular support 12. As shown in FIG. 1, the supply conduit 22 extends through the tubular support 12, within the workpiece W. A port 26 is provided at the end of the supply conduit 22, directly adjacent the mandrel l6, and oriented to discharge lubricant from the conduit directly upon the inside surface of the workpiece W, immediately in advance of the mandrel 16.

A lubricant, such as a viscous oil with suitable additives, is supplied by a lubricating injection assembly 28, comprised of an injector 30 supported on the injector support, an input conduit 32 connected to the support and thence the injector, anon-off control valve 34 between the conduit 32 and the injector 30, through which lubricant is supplied to the injector under pressure, and a discharge conduit 36 connected between the injector 30 and the back end of the supply conduit and mandrel support 22. The manner in which lubricant is supplied to the injector 30 is shown in FIG. 2.

Referring to FIG. 2, a lubricant supply drum 40 is connected directly into a lubricant supply system for the injector 30 through a lubricant dispensing pump 42, a three-way lubricant flow control diaphragm valve 43, a lubricant supply conduit 44 and a return conduit 45. The pump 42 is operated from an air supply 46, for example mill air, at a suitable pressure, for example 40 psi. At all times during operation, the pump 42 supplies lubricant from the drum 40 under pressure through the lubricant supply conduit 44 to the three-way valve 43. In one condition or position, the valve causes lubricant supplied by the pump 42 to be recirculated back to the drum 40, through the lubricant return conduit 45. In a second condition or position, the valve directs the lubricant under pressure to the injector 30, through the input conduit 32. The position or condition of the valve 43 is controlled by pressure from the air supply 46, which in turn is controlled by a solenoid operated control valve 52 in an air supply line 54 to the diaphragm portion of the valve 43. The solenoid control valve 52 is operated in response to a timer mechanism 56 that cycles the supply of lubricant for each workpiece and for each application oflubricant if a number of applications are required for a single workpiece during the drawing operation. The timer 56 also controls the time during which the lubricant supply pressure is supplied to the injector 30, in order to accomplish the objectives of the invention, as will be made clear from the operation of the injector itself.

The construction and operation of the injector 30 is best understood from FIG. 3. The injector 30 has a central chamber 58 divided by a sliding injection piston 60 into a measuring chamber portion 61 and a discharge chamber portion 62. Lubricant is supplied to the injector through the input conduit 32, which is connected through the valve 34 by a coupling 64 to one end of the injector and which forms a supply inlet passage 66, through which flow of lubricant is controlled by a slide valve 68 biased by a compression spring 70 in the chamber 58 to a position closing the supply inlet passage 66. Pressure of the lubricant from the conduit 32 moves the slide valve 68 against the force of the spring 70 so that lubricant will flow through the supply inlet passage and through an internal passage 72 ofthe injector body to the measuring chamber portion 61. This flow of lubricant under pressure forces the injection piston 60 to move within the central chamber in a direction to force lubricant already in the discharge chamber portion 62 from that portion, through an outlet port 74, to which the discharge conduit 36 is connected. It will be understood that lubricant is already in the discharge chamber portion from a previous cycle of operation. Movement of the sliding injection piston 60 eventually results in contact by an extending stem portion 76 of the sliding piston with the slide valve 68. The injector piston, having a greater active area than the slide valve in communication with the lubricant under pressure, moves the slide valve to its closed position, closing the supply inlet passage 66 and stopping movement of the injection piston 60. Both pistons remain in this position as long as the lubricant from the supply pump 42 is supplied through the control valve 43. When the valve 43 is actuated to a closed position,

it shuts off the supply of lubricant through the conduit 32 and vents that conduit through the valve to the lubricant return conduit 45. This permits the compres- I sion spring 70 to move the slide valve 68 to a position where a cross passage 78 and connected axial passage 79 provide a communicating path between the internal passage 72 and the discharge chamber portion 62. At that time, the spring 70 can and does move the sliding injection piston 60 within the central chamber 58, back toward its initial position, forcing lubricant from the measuring chamber portion 61 back through the passage 72 and hence into the discharge chamber portion 62. During this action, the fluid pressure at the outlet port 74 is substantially diminished, to a pressure less than that at the port 26, which forms the discharge for the conduit 36 and connected mandrel support 22.

In operation, the control valve 43 is actuated by the solenoid operated control 52 from the timer mechanism 56, in accordance with a preset timer cycle. This cycle controls the intervalof successive injections of lubricant from the injector and hence from the port 26 adjacent to the workpiece W. The amount of lubricant discharged is controlled by the injector capacity. The timer mechanism also controls the time during which lubricant is supplied under pressure to the injector 30 through the conduit 32.

From the description of the injector 30, it will be apparent that the time during which lubricant is supplied under pressure to the injector through the passage 32 will not affect the amount of lubricant discharged by the injector. However, the maintenance of pressure to the injector, i.e., the provision of a delay before the pressure to the injector is relieved through venting of the supply conduit 32 through the valve 43, has been found to provide a way in which this injector can accurately control the amount of lubricant discharged and to effectively prevent afterflow or dripping of lubricant through the orifice 26 to the workpiece W.

When the timer mechanism 56 produces a signal to begin a lubricating cycle, air from the supply 46 is supplied under pressure through the solenoid control valve 52 to the lubricant flow control diaphragm valve 43. The air supply actuates the valve 43, moving it from a position in which lubricant is recycled by the pump 42 back to the drum 40, to a position in which lubricant is supplied under pressure to the conduit 32 and to the injector 30. As a result, the injector 30 functions in the manner already described above and lubricant is injected through the outlet port 74 of the injector, through the conduit 36 and mandrel support 22, and is discharged from the port 26 onto the inner surface of the workpiece W adjacent the mandrel and die.

The timer mechanism 56 is set to keep the air control valve 52 and the lubricant control valve 43 in the supply position for a predetermined time. This time period depends upon the viscosity of the lubricant and the characteristics of the supply passageway to the port 26, and therefore must be determined through experimentation for each system. The time must be sufficient for the residual pressure within the conduit system, from the injector to the port 26, to substantially dissipate continuously after the injection piston 60 of the injector reaches the end of its travel in the injection cycle. By substantially dissipate is meant that the pressure dissipates to the extent that it is low enough that the subsequent decrease in pressure at the outlet port 74 of the injector, when the supply pressure to the conduit 32 is stopped, will reduce the total pressure in the conduits 22 and 36 from the injector to less than the pressure outside the orifice 26. As a result, lubricant within the conduit 22 will be drawn back from the port 26 and there will be no tendency for lubricant to drip.

At the end of this delay period, the timer mechanism actuates the solenoid control valve 52 to change the condition of the lubricant flow control valve 43 to relieve the lubricant pressure to the injector and to vent the supply conduit 32, causing the pressure reduction and affect described above. The timer then, after a further programmed delay, will cause the injector 30 to recycle, by supplying a lubricant again through the conduit 32, and will maintain the pressure for the same period of delay to achieve the same result described above, for the next cycle. The cycle time between injections of lubricant will depend upon whether more than one injection is needed for the drawing operation of any particular workpiece W, or whether additional time must be allowed for changing the workpiece. In any event, the timer mechanism has the flexibility to provide both the delay period during which pressure is maintained to the injector 30 and also a recycling schedule programmed to the drawing operation. Timer mechanisms having these capabilities are of course well known and the mechanisms have not been described in detail.

From the foregoing description it will be appreciated that a new system and process of supplying lubricant to a workpiece in a drawing operation have been provided which accomplish the objectives previously referred to and others. While a preferred embodiment has been described in detail it will be understood that various modifications or alterations may be made therein without departing from the spirit or scope of the invention set forth in the appended claims.

What is claimed is:

1. In the art of metal drawing, a method of supplying a measured quantity of lubricant to the metal during drawing, the steps comprising: segregating a measured quantity of lubricant from a source; injecting the quantity under pressure into a passage having a discharge adjacent the metal being drawn, causing flow of lubricant from the passage; and after a predetermined time delay subsequent to completion of the injecting, temporarily reducing the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop flow of lubricant from the discharge, whereby the amount of lubricant discharged from the passage is accurately controlled.

2. The method as set forth in claim 1 including the steps of subsequently injecting a second quantity equal to the first into the passage under pressure after a predetermined time interval following the first injecting step and during which the metal is partially drawn; after a predetermined time delay equal to the first and following completion of the second injecting of lubricant, temporarily reducing the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop the flow of lubricant and assure that the quantity discharged is equal to that discharged in response to the first injecting step.

3. In the art of metal drawing, a method of supplying a measured quantity of lubricant to the inside of a tubular metal piece being drawn over a mandrel and through a die, the steps comprising: providing an injector that receives and measures a predetermined quantity of lubricant supplied under pressure, forces only the predetermined quantity under pressure through a discharge passage, and in response to reduction of the supply pressure temporarily reduces the pressure at the discharge passage; supplying lubricant under pressure to said injector at predetermined time intervals to force said predetermined quantity through the discharge passage; conducting the discharged quantity of lubricant through a conduit to a location within the tubular metal piece adjacent to the mandrel and drawing die to lubricate metal being drawn; and reducing the supply pressure of the lubricant t the injector each time lubricant is supplied, but only after a predetermined time delay following injection of lubricant by the injector through the discharge passage, whereby the injector reduces the pressure at the dischargepassage and the combined loss of pressure in the discharge passage due to continued flow of lubricant during the time delay and the pressure reduction from the injector stops further flow of lubricant to the metal until lubricant is again supplied to the injector.

4. In the art of metal drawing, apparatus for supplying a measured quantity of lubricant to the metal during drawing, comprising: a source of lubricant, a lubricant passage having a discharge adjacent the metal being drawn, injector means connected between said source and said passage for segregating a measured quantity of lubricant from a source and injecting the quantity under pressure into the passage, causing flow of lubricant from the passage; timer means for establishing a predetermined time delay subsequent to completion of the injection and for then controlling the lubricant supply to temporarily reduce the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop flow of lubricant from the discharge, whereby the amount of lubricant discharged from the passage is accurately controlled.

5. In the art of metal drawing, apparatus for supplying a measured quantity of lubricant to the inside of a tubular metal piece being drawn over a mandrel and through a die, comprising: an injector adapted to receive and measure a predetermined quantity of lubricant supplied under pressure, force only the predetermined quantity under pressure through a discharge passage, and in response to reduction of the supply pressure temporarily reduce the pressure at the discharge passage; means to supply lubricant under pressure to said injector at predetermined time intervals to force said predetermined quantity through the discharge passage; a conduit from said discharge passage for conducting the discharged quantity of lubricant to a location within the tubular metal piece adjacent to the mandrel and drawing die to lubricate metal being drawn; and control means including an air-actuated timercontrolled valve for controlling the lubricant supply operable to reduce the supply pressure of the lubricant to the injector each time it is supplied but only after a predetermined time delay following injection of lubricant by the injector through the discharge passage, whereby the injector reduces the pressure at the discharge passage and the combined loss of pressure in the discharge passage due to continued flow of lubricant during the time delay and the pressure reduction from the injector stops further flow of lubricant to the metal until lubricant is again supplied to the injector. 

1. In the art of metal drawing, a method of supplying a measured quantity of lubricant to the metal during drawing, the steps comprising: segregating a measured quantity of lubricant from a source; injecting the quantity under pressure into a passage having a discharge adjacent the metal being drawn, causing flow of lubricant from the passage; and after a predetermined time delay subsequent to completion of the injecting, temporarily reducing the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop flow of lubricant from the discharge, whereby the amount of lubricant discharged from the passage is accurately controlled.
 2. The method as set forth in claim 1 including the steps of subsequently injecting a second quantity equal to the first into the passage under pressure after a predetermined time interval following the first injecting step and during which the metal is partially drawn; after a predetermined time delay equal to the first and following completion of the second injecting of lubricant, temporarily reducing the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop the flow of lubricant and assure that the quantity discharged is equal to that discharged in response to the first injecting step.
 3. In the art of metal drawing, a method of supplying a measured quantity of lubricant to the inside of a tubular metal piece being drawn over a mandrel and through a die, the steps comprising: providing an injector that receives and measures a predetermined quantity of lubricant supplied under pressure, forces only the predetermined quantity under pressure through a discharge passage, and in response to reduction of the supply pressure temporarily reduces the pressure at the discharge passage; supplying lubricant under pressure to said injector at predetermined time intervals to force said predetermined quantity through the discharge passage; conducting the discharged quantity of lubricant through a conduit to a location within the tubular metal piece adjacent to the mandrel and drawing die to lubricate metal being drawn; and reducing the supply pressure of the lubricant to the injector each time lubricant is supplied, but only after a predetermined time delay following injection of lubricant by the injector through the discharge passage, whereby the injector reduces the pressure at the discharge passage and the combined loss of pressure in the discharge passage due to continued flow of lubricant during the time delay and the pressure reduction from the injector stops further flow of lubricant to the metal until lubricant is again supplied to the injector.
 4. In the art of metal drawing, apparatus for supplying a measured quantity of lubricant to the metal during drawing, comprising: a source of lubricant, a lubricant passage having a discharge adjacent the metal being drawn, injector means connected between said source and said passage for segregating a measured quantity of lubricant from a source and injecting the quantity under pressure into the passage, causing flow of lubricant from the passage; timer means for establishing a predetermined time delay subsequent to completion of the injection and for then controlling the lubricant supply to temporarily reduce the pressure in the passage upstream from the discharge to a pressure less than that at the discharge to stop flow of lubricant from the discharge, whereby the amount of lubricant discharged from the passage is accurately controlled.
 5. In the art of metal drawing, apparatus for supplying a measured quantity of lubricant to the inside of a tubular metal piece being drawn over a mandrel and through a die, comprising: an injector adapted to receive And measure a predetermined quantity of lubricant supplied under pressure, force only the predetermined quantity under pressure through a discharge passage, and in response to reduction of the supply pressure temporarily reduce the pressure at the discharge passage; means to supply lubricant under pressure to said injector at predetermined time intervals to force said predetermined quantity through the discharge passage; a conduit from said discharge passage for conducting the discharged quantity of lubricant to a location within the tubular metal piece adjacent to the mandrel and drawing die to lubricate metal being drawn; and control means including an air-actuated timer-controlled valve for controlling the lubricant supply operable to reduce the supply pressure of the lubricant to the injector each time it is supplied but only after a predetermined time delay following injection of lubricant by the injector through the discharge passage, whereby the injector reduces the pressure at the discharge passage and the combined loss of pressure in the discharge passage due to continued flow of lubricant during the time delay and the pressure reduction from the injector stops further flow of lubricant to the metal until lubricant is again supplied to the injector. 